My colleagues in the Centre for Development of Open Technology have been doing some amazing work enhancing the open web. One of their libraries, Popcorn.js, enables web video to move beyond being a box on the page to become a part of the hyperlinked, dynamic web. With a ton of frantic hacking by the Popcorn team which began on Tuesday morning (!), PBS launched an interesting web page that night showing analyst's comments synchronized to a video of the US President's State of the Union speech. PBS comments about the effort are posted on The Rundown.
You should check out what these folks are doing with 3D on the web -- the Javascript port of the Processing data visualization language, Processing.js -- point cloud data -- and web audio!
Update: Dave Humphrey has blogged about the work that he and his team did on the SOTU page with PBS.